Performance-Enhanced Polysilicon Microbolometer in CMOS Technology With a Grating Structure

Abstract

The resistive microbolometer fabricated by using CMOS technology can be monolithically integrated with the readout circuit but usually performs poorly in responsivity and detectivity. In this paper, the salicide poly-Si microbolometer with Al grating structure is demonstrated in the standard CMOS process. The simulation results show that not only are surface plasmon polaritons generated at the interface of the Al grating and SiO2, Al grating also provides the infrared resonant cavity required for the absorber, which improves the responsivity of the microbolometer. According to the experimental results, the maximum detectivity of the microbolometer with the grating structure reaches up to 2.26 × 109 cmHz1/2/W at 10 μm, which means an increase by 27.8% compared to the one without the Al grating. Moreover, the average detectivity of the microbolometer is also improved when the wavelength ranges from 7 μm to 13 μm. It is effortless to implement the proposed high-performance microbolometer in a unit structure based on CMOS technology, which is favorable to high-density array integration.

Keywords

• Al grating
• CMOS process
• microbolometer
• resonant cavity
• salicide poly-Si thermistors